The richer the assortment of amphibian species in a pond, the more protection that community of frogs, toads and salamanders has against a parasitic infection that can cause severe deformities, including the growth of extra legs.
The findings, published in a paper in this week's issue of the journal Nature, support the idea that greater biodiversity in large-scale ecosystems, such as forests or grasslands, may also provide greater protection against diseases, including those that affect humans.
A larger number of mammal species in an area may curb cases of Lyme disease, while a larger number of bird species may slow the spread of West Nile virus.
"How biodiversity affects the risk of infectious diseases, including those of humans and wildlife, has become an increasingly important question," said Pieter Johnson, an ecologist and evolutionary biologist at the University of Colorado Boulder, and the lead author of the paper.
"But as it turns out, solidly testing these links with realistic experiments has proven very challenging in most systems."
Researchers have struggled to design comprehensive studies that could illuminate the possible connection between disease transmission and the number of species living in complex ecosystems.
Part of the problem is the enormous number of organisms that may need to be sampled, and the vast areas over which those organisms may roam.
This study overcame that problem by studying smaller, easier-to-sample ecosystems, the scientists say.
"The research reaches the surprising conclusion that the entire set of species in a community affects susceptibility to disease," said Doug Levey, program director in the National Science Foundation (NSF)'s Division of Environmental Biology, which funded the research. "Biodiversity matters."
Johnson and colleagues visited hundreds of ponds in California, recording the types of amphibians living there as we
|Contact: Cheryl Dybas|
National Science Foundation